Micr imprinting photo-etched credit card

ABSTRACT

A personal credit card for use in a hand operated imprinter for placing MICR and OCR encoding on business documents through a suitable carbon comprises a balanced laminated structure of a PVC core having a light insensitive nylon film adhesively bonded on each side. A film of a photo-polymerizable nylon is autogeneously bonded to one of the light insensitive films. The reverse side of the photo-polymerizable film is lightly exposed prior to the autogeneous bonding. The obverse photosensitive side of the film is exposed through a negative containing the requisite visually readable and machine-readable types of characters, and the unexposed background areas are then removed by solvent washing to leave the characters in relief. The prior exposure of the reverse side of the photosensitive film permits &#39;&#39;&#39;&#39;over etching,&#39;&#39;&#39;&#39; i.e., allows more tolerance in the etching step and assures that 100 percent contact between the two nylon films remains at the autogeneous bond minimizing penetration of the solvent to the sub film and assuring good support of the relief characters.

United States Patent Bradford [4 Nov. 28, 1972 [54] MICR IlVIPRINTING PHOTO-ETCHED Primary Examiner-David Klein CREDIT CARD Attorneybee A. Strimbeck [72] Inventor: eRams/try Bradford, Falmouth, [57] ABSTRACT A personal credit card for use in a hand operated im- [73] Assxgnee' Corporation printer for placing MICR and OCR encoding on busi- 6 ea ness documents through a suitable carbon comprises a [22] Filed: Nov. 2, 1970 balanced laminated structure of a PVC core having a light insensitive nylon film adhesively bonded on each [21] Appl' 86257 side. A film of a photo-polymerizable nylon is autogeneously bonded to one of the light insensitive 52 us. Cl. ..101/369, 101/401.1, 96/363 fi The reverse e of the Phetepelymerizable film 51 1m. 01. ..B4ll 47/02, G030 5/00, G03f 7/00 15 hghfly exposed p h auteseheeue bending- [58] Field of Search 101 /401.1, 369; 96/363, 35.1, The obverse pheteeehslhve slde 9f the film 1s exposed 96/115 F through a negative containing the requisite visually readable and machine-readable types of characters, [56] References Cited and the unexposed background areas are then removed by solvent washing to leave the characters in UNITED STATES PATENTS relief. The prior exposure of the reverse side of the photosensitive film permits over etching, i.e., allows Q i: more tolerance in the etching step and assures that 32l7643 11/1965 c 4O1'l 100 percent contact between the two nylon films 3 flssy at remains at the autogeneous bond minimizing penetra- 3 349 O 101/ tion of the solvent to the sub film and assuring good 7 6 6 v 1 6 6 1 I 6 rt f th 1' f h t 3,029,920 4/1962 Seifried ..10l/369 X Suppo o e re 6 am ers 45-49 mils CHARACTER, 27

2 Claim, 3 Drawing Figures PHOTO-POLYMERIZED NYLON, 2e

WELDED BOND NYLON 6, 24

HEAT SENSITIVE ADHESIVE 22 VINYL BACKING, 2|

HEAT SENSITIVE ADHESIVE, 23

NYLON 6, 25

PATENTEU W28 I972 3.703.864

SHEET 1 OF 2 =JAMES DOE 4 69 M05 E/ bfl 50m q qfiaxs J CHARZAISITER, PHOTO-POLYMERIZED NYLON, 26

45-49 mils WELDED BOND NYLON 6, 24

k HEAT SENSITIVE W ADHESWE 22 1' 7////7///AmNYLON 6, 25

Fwmus FIG. 2

INVENTOR JOHN R. BRADFORD fie 64.

ATTORNEY PATENTEDNUV28 I972 3 703, 864

SHEET 2 OF 2 DISSOLVE NYLON 33 COAT NYLoN e FILM PELLETS IN METHYL WITH HEAT- ALcoHoL WITH SENSITIVE HEATING uNDER ADHESIVE REFLUX ADD PHOTO-ACTIVE /34 INGREDIENTS wITH HEATING AND STIRRING I II BOND NYLoN FILM /35 CAST FILM ON To BOTH SIDES /32 MYLAR BELT OF PREPRINTED AND GEL DRY PVC BACKING SHEET TWO RoLL DRuM DRY WET SURFACE ,3? wITH HEXAFLUORO- MILDLY LIGHT- 38 ISOPROPANOL EXPOSE JUST PRIOR TO REVERSE SIDE coNTAcT 7 ROLL BOND 4 II WITH PRESSURE THROUGHLY DRY INvENToR FIG. 3

JOHN R. BRADFORD ATTOR N EY MICR IMPRINTING PHOTO-ETCIIED CREDIT CARD PREAMBLE MICR and OCR encoding of documents to make them machine-readable has been in use for some time, especially in connection with bank checks. The MICR encoding is usually placed on the documents under controlled conditions as by offset printing or typing through a special MICR ribbon. MICR encoding in the field such as in point of sale recording using a credit card and a hand imprinter has not proved to be practical because of the unacceptable variations in the encoding from document to the document. OCR encoding in the field is practiced, but the reject rate of the so encoded documents on OCR reading machines is undesirably high.

Among other things, it has been found that the character or quality of such credit card encoding can be improved if the type characters on the card are sharp and well defined, embossed characters generally being unsatisfactory in this respect, and if the characters be properly sized to allow for character growth when imprinting through a carbon paper. Also, since a credit card is used many, many times during its life, the quality of the characters must not deteriorate during use and the card should have a resiliency to abuse occassioned by being carried and handled and by the stress placed on it during each imprinting use. For example, a loss of only 4 to 5 thousandths of an inch in thickness because of surface wear and/or card compression can drastically affect the quality of printing because most hand imprinters will not tolerate substantial variations in card thickness as they are preset for a card of a fixed or given thickness in order to generate the correct printing pressure.

This invention proposes a credit card type of photoetched printing plate that meets these and other desiderata.

RELATED APPLICATIONS Roller lmprinter for Pocket Credit Card, filed simultaneously herewith by John Bradford and William Goodwin Ser. No. 85,947, now U.S. Pat. No. 3,656,429, issued Apr. 18, 1972 describes one type of hand imprinter that can usefully employ the credit card of this invention.

MICR Encoding with Credit Card and Form-set, filed simultaneously herewith by John Bradford and William Stevenson S.N. 85,948, describes one particular method of employing a credit card of the type here contemplated, using a certain formset of the machine processable business document, tissue copies and interleaved carbons.

Photosensitive Compositions, by Margaret Murray and Robert Leckely, Ser. No. 633,731, new abandoned, assigned to Time, Incorporated and licensed to the assignee of this application, describes one type of photosensitive nylon composition of interest.

PRIOR ART U.S. Pat. Nos. 2,997,391; 3,081,168; and 3,474,071 assigned to Time, Incorporated, describe suitable photosensitive nylon films of interest, particularly U.S. Pat. No. 3,081,168 on which the following example is based.

U.S. Pat. No. 3,217,643, by Robert Crissy and Joseph Gilligan describes one types of MICR encoded photo-etched credit card. Since the patent lacks a specific example of a suitable etchable composition, it is not known whether the proposed structure is feasable. In any event, it is clear that this patent is not concerned with the specific type of balanced laminatephoto-etched nylon surface structure here proposed.

U.S. Pat. No. 3,272,120, by Dean Johnson describes another type of imprinter that could usefully employ the credit card of the invention, and well describes some of the problems encountered in this type of MICR imprinting.

THIS INVENTION This invention is a nylon type, i.e., one having a nylon printing surface, photo-etchable printing plateof balanced laminated construction, particularly useful as a MICR or OCR encoding pocket credit card but also useful in any printing situation where a sharp, well defined relief surface that is tough and longwearing is required.

The plate comprises:

a. a backing sheet as of metal, paper, polyethylene, but preferably of a polyvinyl chloride as is now customarily used for embossed cards as this has the requisite toughness and flexibility to suit it for the abuse of repeated handling;

b. a coextensive covering on each side of a substantially light insensitive nylon film bonded with a heat sensitive adhesive, preferably a nylon-6 film, 1 to 5 mils thick; and

c. on one surface, an autogeneously bonded cast or extruded photopolymerizable 10 to 40 milv film of a nylon and a photo initiator, the reverse side of which has been mildly exposed to light prior to the autogene-.

ous bonding while leaving the obverse side still amenable to photo-polymerization.

By partially exposing the reverse side of the photosensitive film, the solvent used for etching or developing the characters on the obverse side, after light exposure thereof through a negative, will not remove the base layer of the top film adjacent to the nylon-6 sub film so that over etching is not a critical consideration and a portion of the top film remains to give good support to the etched characters. Preferably, the pre-exposure is sufficient to permit at least 25 percent of the original thickness to remain after the etching step.

The photo-polymerizable and the light insensitive films are preferably autogeneously bonded through the application of a mutual solvent to one of the surfaces and bringing them together under pressure, followed by slow drying to evaporate the solvent through the film.

The credit card of a preferred embodiment is a multifunctional card that, in addition to containing a line of machine-readable alpha-numeric or MICR code and a line or more of conventional visually readable characters such as the persons name, also contain a line of OCR numbers. In addition, it can contain a line of fine segments arranged in a binary, dot-dash, or similar code. All such lines are made at one time by photoetching.

The printing plate of this invention has several advantages. The type characters in relief on the surface are well formed, are consistent and of a precise height from plate to plate and are well bonded and supported by the underlying material. The printing surface is tough and abuse resistant and will last through a considerable number of impressions with negligible surface wear. The plate as a pocket credit card will accept the bending and flexing occassioned by the usual carrying and handling, and will not undergo a noticeable decrease in thickness despite repeated imprinting in hand imprinters. It is also useful over a wide range of temperatures without either inacceptable cold embrittlement or temperature softening.

It has been found that even though the credit card be repeatedly flexed to the point where the PVC bonding sheet cracks, the bonded nylon-6 films retain the integrity of the card so that the cracks are not detrimental, in fact, hardly noticeable.

The present process of credit card manufacture is amenable to rapid and straightforward manufacture of the large number of individual cards required for any credit card system by photo composing a single negative for a large block of cards, followed by exposing and etching of a large sheet of the instant laminate, and then die cutting of each individual card.

THE DRAWINGS In the drawings:

FIG. 1 is a top view of one type of credit card made in accordance with this invention;

FIG. 2 is a greatly enlarged schematic cross section of the printing plate; and

FIG. 3 is a block flow diagram of the steps of manufacture.

DESCRIPTION With reference to FIG. 1, the card consists of the laminate structure of this invention having etched on its surface the requisite lines of characters for imprinting visual and/or machine-readable information onto a business document through either a conventional carbon sheet or a MICR carbon sheet. Normally a card will have one or more lines 11 of right-reading alpha-numeric information identifying the card holder and possibly the issuance or expiration date of the card as at 13. In accordance with this invention, the card also contains a line 12 of MICR characters or a line 14 of OCR characters, or both. In the card illustrated, the MICR characters, such as of the type l3-b font approved by the American Bankers Association, are in reverse reading mirror image suited for imprinting on the reverse side of a business document through a MICR carbon, while the remainder of the information is printed with the aid of a conventional carbon on the obverse side.

As illustrated, the card also contains a pressure leveling lands or ridges 15 extending parallel to line 12 a distance at least equal to the length of the clear band. This land 15, especially in conjunction with a similar land on a fixed information plate in a hand imprinter, helps to equalize the pressure exerted on the characters, especially in cases where there is some misalignment of the roller platen. Also, it helps to avoid any smudging of the background areas in the clear band. While 15 is shown as solid, it could as well consist of a series of fine parallel lines, say three, and/0r it can be a bar code, i.e., be vertically segmented to yield, for example, a binary code upon imprinting through a MIC carbon an thus give an additional method of machine readability. In this connection, line 15 can be made magnetically sensible as by being tipped with a MICR ink and overcoated with a scuff coat or by lightly pigmenting the top surface prior to etching with a magnetic oxide, so that the card itself is readable by an induction head, as in the manner of U.S. Pat. No. 3,325,632 (Lilly).

In order to keep the printing area relatively constant, it is desirable in some cases to place flags or additional bands at the terminus of lines shorter than the MICR line 12, such as at 16 and 17.

Referring to FIG. 2, the printing plate in cross section is a laminate consisting of a backing layer 21, preferably a PVC sheet, on both sides of which is solvent appliedheat sensitive coatings 22 and 23 to which are bonded films 24 and 25 of nylon-6. On the top surface is autogeneously bonded or welded a photosensitive nylon film 26, having etched thereon type characters 27. As shown, a portion of the photo-polymerized nylon remains after etching assuring good bonding to the nylon sub-layer 24 and protection thereof, and good physical support of the characters 27 Typical dimensions are given on the drawing.

Turning to FIG. 3, the balanced laminated structure is prepared by coating at 31 a 2 mil nylon-6 film, Capram-77 (Allied Chemical Co.) with a solvent-applied heat sensitive adhesive. A suitable adhesive coating is 0.4 mil (dry) of Boscodur 7075 followed by onehalf mil (dry) of Boscodur No. 1 (United Shoe Co.), which is a solvent-based urethane type adhesive system.

In step 32, the thus coated film is applied to both sides of a heavily pigmented vinyl sheet, which may be preprinted as with a logo. Suitable heat and pressure is used, such as that given by a calender. A suitable vinyl sheet is one customarily used to prepare embossed credit cards, for example, 25 mil Bakelite Rigid Vinyl Sheet- VCA 3603 (Chemicals and Plastics Division, Union Carbide Corp.). A metal backing is not preferred for credit card use as it too readily takes a permanent bend or set. The laminated structure, balanced as to film thickness and type, in FIG. 2 is preferred to avoid subsequent warping or edge curl.

The photo polymerizable nylon film is prepared according to U.S. Pat. No 3,081,168 (see Example 18) by first, in step 33, dissolving commercially available nylon pellets of hexamtheylene-diammonium adipate, hexamthylene-diammonium sebacate and caprolaction (40:30:40) copolymer, e.g., Zytel 63 (E.I. duPont de Nemours and Co.), in equal parts by weight of methanol solvent by heating under reflux.

The photo active ingredients are then added to the solution in step 34. On the basis of parts by weight (PBW) of nylon resin, these consist of:

PB! Compound Purpose 5.0 N,N'-hexamethylene Reactive photobisacrylamide monomer 5.0 benzophenone photo initiator 0.05 hydroquinone inhibitor Continued heating and stirring is used to effect solution.

The solution is then cast under a blade onto a belt, e.g., a Mylar belt. It can be cast, for example, as a 47 mil wet film design to yield a 17 mil dry film. The cast film is removed as soon as possible from the belt so that it can dry uniformly from both surfaces. With a belt travel of 4 feet per minute, this can be done after about feet as soon as the solution has lost enough solvent to gel firmly.

Thereafter, what is to be the reverse side of the film is mildly exposed to light. For example, it is passed under a bank of five fluorescent black lights (General Electrics BL) drawing 4 watts at a distance of 0.5 inch for a total exposure time of 5 seconds. Preferably the exposure is sufficient so that 0.5 to 50 percent, preferably at least 25 percent, of the original film thickness (dry) will remain after exposing and developing the obverse side this can be determined by routine experimentation.

The thus prepared photo polymerizable film is then bonded to the vinyl-nylon sheet. This is done by contacting the two surfaces of the films of the like polymers with a known mutual solvent, e.g., hexafluoroisopropanol, phenol, formic acid, etc. As illustrated at steps 38 and 29 the film and the sheet are bought together by passing under a pressure roll. Since the preferred solvent, hexafluorisopropanol, is extremely volatile, the reverse surface of the film is wetted with the solvent just immediately prior to the nip formed by the sheet and the film, as by being applied by a small kiss roll.

When brought together in this manner, the two nylon film surfaces weld immediately. The completed card stock is then allowed to dry slowly over a period of days in step 40 to permit the solvent to migrate through and from the photo polymerizable film.

All of the steps from 34 on are carried out in dim yellow light, except 37.

The card stock from step 40 is then used to prepare printing plates-credit cards such as illustrated in FIG. 1, and the like in a conventional manner by exposing the surface through a negative containing the requisite information, and developing the surface by washing away with a solvent that dissolves the unexposed areas and leaves the exposed areas, e.g., with methanol containing 3 grams of dissolved calcium chloride/liter anhydrous methanol.

The characters 27 will usually have a height of 5 to mils, approximately 40 to 60 percent of the original thickness of the film 26, which will normally be in the range of 10 to 50 mils thick (dry).

The photo polymerizable film 26 as is known, can contain additives to impart color, fillers to impart wear resistance and strength, magnetic properties (iron oxide), radiation properties (lead; boron-l0 and the like. If the obverse surface of the film is colored, then the credit cards prepared therefrom are self-tipping. The same effect can be achieved by bonding two or more thin layers of photo polymerizable nylon film to the base sheet, with only the upper film being colored or pigmented.

While this invention is particularly directed to the manufacture of pocket credit card printing plates, the semi-exposed photosensitive nylon film can, of course, be bonded, either directly as with heat and pressure or indirectly as with an adhesive, to any suitable backing such as an anodized aluminum or parkerized steel sheet. In some cases, the photo insensitive nylon-6 films can be done away with or can be replaced with vinyl,

ABS or other plastic films, and the backing member can be a cardboard or like material.

COMPARATIVE TESTING The credit card of this invention having an OCR code was directly compared to an embossed OCR card in use by a major oil company. Three of each type of card, newly prepared, were compared using three different formsets, three temperature conditions (20F, F and F), and three shim conditions (to vary the clearance between the roller plate and the bed, and thus the imprinting pressure).

The card of this invention was prepared as described in connection with FIG. 3, and the land 15 (FIG. 1) consisted of 3 fine rails one-fourth inch below the OCR characters with flags 15 being used as required. The correct reading OCR characters had an etched height of 12 mils.

Twenty-five documents were prepared from each set of the cards under each of 27 different conditions, for a total of 675 for the card of this invention and 675 for the conventional card; or 225 for each of the 6 cards tested.

In all cases imprinting was started with two shims, then one shim and finished with no shims. The formsets were the normal two-part formset used by the oil company with an average thickness of 0.010, a special three-part from set using 28 pound paper as the processing copy with a total thickness of 0.010, and finally the same formset with a top sheet removed giving a thickness of 0.009. Paper shims were used since they simulate the lubrication stickers common at gas stations. The 20 condition was achieved in a horizontal freezer. The cards, imprinter and formsets were maintained overnight in the freezer before imprinting was t begun. The 70 setting was used in a laboratory with no special care taken. The 120 environment was reached under a bank of heat lamps controlled by a thermocoupie.

The documents were run through an REI reader under a special test program and all characters were printed out. Only one pass was made.

Thickness measurements of the cards before and after this series of tests showed no loss of thickness for the present card under any conditions; about a 0.001 loss from initial 0.046 height for the 20 and 70 conditions for the oil company card and about 0.003 loss at 120. Some of the characters on the conventional card, however, obviously lost more than this since they failed to print under the no-shim condition.

In terms of the number of documents rejected, the greatest single cause of rejections of the conventional card was nonprinting caused by debossing of the card. The other major cause was background pickup under the heavy shimming conditions.

Twelve of the documents produced with the etched cards were rejected for an overall document acceptance rate of 98.2 percent. The conventional cards produced 158 rejects for an overall document acceptance rate of 76.6 percent.

The oil company testing lab had developed a system of weighting the results under each condition which, although arbitrary, seemed reasonable. The greatest weight was given to the no-shim 70 condition, this being given a weight of 30; second, 70 with one shim at a weight of 18; third, 120 at no shim at a weight of 15, etc. Using the weighted averages, the embossed cards produced an accept rate of 76.9 percent and cards of this invention produced a 98.96 percent accept rate.

Thus by changing only one element in the oil companys present system, i.e., use of photo-etched cards in place of its present embossed cards, the reject rate could be cut by a factor greater than 10.

What is claimed is:

1. A flexible laminated nylon-type photo-etched credit card printing plate suitable for use in a roller imprinter to encode a business form with a machinereadable code, consisting of:

a. a flexible plastic backing sheet,

b. a coextensive substantially light-insensitive nylon base film in the range of 1 to 5 mils thick bonded to each side of said backing sheet with a thin heatsensitive adhesive film, and

c. a coextensive light exposed and solvent-etched originally photosensitive nylon film in the range of to 50 mils thick directly bonded to one side of the laminate of (b) without the use of a bridging adhesive, said photosensitive nylon film comprising a mixture of a nylon resin with minor but efi'ective amounts of a reactive photomonomer and a photo initiator;

the reverse side of said originally photosensitive nylon film being photo polymerized uniformly across the surface thereof to a depth of at least 25 percent of the thickness of the film and the obverse side thereof being light exposed through a negative and solvent etched to have in relief at least one line of correct reading alpha-numeric type characters and at least one line of reverse mirror image reading machine-readabletype characters, said type characters having a thickness in the range of 5 to 20 mils, said reverse side being in continuous coextensive contact with said base film and affording good support forsaid type characters.

2. The printing plate of claim 1 wherein said photosensitive nylon film also contains a minor but effective amount of an inhibitor and said obverse side also contains pressure equalizing lands. 

2. The printing plate of claim 1 wherein said photosensitive nylon film also contains a minor but effective amount of an inhibitor and said obverse side also contains pressure equalizing lands. 